This application claims the priority of German patent document 100 13 687.7, filed Mar. 21, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a fuel cell system having a facility for humidifying process gases to provide fuel for the fuel cell itself.
To prevent the electrode membrane from drying out it is necessary in fuel cells, particularly in those comprising proton-conducting electrolyte membranes (PEM cells), to humidify the process gases such as air or fuel gas. Water produced in the fuel cell, which is customarily extracted from the fuel cell off-gas by means of a water separator, can be used for this purpose, as disclosed, for example in European patent document EP 0 629 014 B1.
Particularly in mobile fuel cell systems comprising proton-conducting electrolyte membranes, high requirements are placed on the control of water balance.
Accordingly, it is an object of the invention to provide a fuel cell system with an improved supply of process water at low temperatures.
This and other objects and advantages are achieved by the fuel cell system according to the invention, in which heatable media conduits are provided downstream of a fuel cell unit, which media conduits are at least partially heatable. This structure has the advantages that process water in the media conduits can be kept liquid independently of ambient conditions, and that the risk of blockages, due to freezing water, of media conduits and/or of valves and pumps disposed in the media conduits is avoided.
Further advantages and refinements of the invention can be gathered from the further claims and the description.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.